Various types of rolling doors have long been used to selectively open and close a doorway or other opening in a structure. A potential exists for damage to the door, the structure, as well as injury to users near the rolling door, in the event of an uncontrolled closing/dropping of the door. In an attempt to minimize and/or prevent such uncontrolled movement, door stop mechanisms have been created to stop and/or otherwise prevent this unintended downward movement of the door.
Many existing door stop mechanisms; however, fail to quickly stop the downward movement, lack or have unsatisfactory redundant/back-up stop mechanisms, and are difficult to accurately calibrate. For example, as a door drops, especially a door of increased weight, it gains momentum and thus speed thereby becoming increasingly more difficult to stop such motion. When the door stop mechanism attempts to stop the door, the door oftentimes will “bounce back” (i.e., upon initial contact, the door will abruptly contact the door stop apparatus and bounce or otherwise move in the upward/opposite direction, eventually settling back against the door stop), which can damage the door and/or the door stop mechanism.
Thus, it would be beneficial to have a mechanism suitable for all conditions of service that, among other things, is operable to quickly stop a door that is uncontrollably closing, includes a back-up/redundant stop mechanism, and allows for precise calibration.